Windows 2000-based computers support several methods of controlling inbound access. One of the most simple and most powerful methods of controlling inbound access is by using the TCP/IP Filtering feature. TCP/IP Filtering is available on all Windows 2000-based computers that have the TCP/IP stack installed.
TCP/IP Filtering is useful from a security standpoint because it works in Kernel mode. In contrast, other methods of controlling inbound access to Windows 2000-based computers, such as by using the IPSec Policy filter and the Routing and Remote Access server, depend on User-mode processes or the Workstation and Server service.
You can layer your TCP/IP inbound access control scheme by using TCP/IP Filtering with IPSec filters and Routing and Remote Access packet filtering. This approach is especially useful if you want to control inbound and outbound TCP/IP access. TCP/IP Security controls only inbound access.
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Start, point to
Control Panel, and then double-click
Network and Dial-up Connections.
- Right-click the interface on which you want to configure inbound access control, and then click
- In the
Components checked are used by this connectionbox, click
Internet Protocol (TCP/IP), and then click
- In the
Internet Protocol (TCP/IP) Propertiesdialog box, click
- Click the
TCP/IP filtering, and then click
- Select the
Enable TCP/IP Filtering (All adapters)check box. When you select this check box, you enable filtering for all adapters, but you configure the filters on a per-adapter basis. The same filters do not apply to all adapters.
- There are three columns with the following labels: TCP PortsIn each column, you must select either of the following options:
IP ProtocolsPermit All. If you want to permit all packets for TCP or UDP traffic, leaveIf you want to block all UDP or TCP traffic, click
Permit Only. If you want to allow only selected TCP or UDP traffic, click
Permit Only, click
Add, and then type the appropriate port in the
Add Filterdialog box.
Permit Only, but do not add any port numbers in the
TCP Portcolumn. You cannot block UDP or TCP traffic by selecting
IP Protocolsand excluding IP protocols 6 and 17.
Note that you cannot block ICMP messages, even if you select
Permit Onlyin the
IP Protocolscolumn and you do not include IP protocol 1.
back to the topFor additional information about IP number assignments, click the following article number to view the article in the Microsoft Knowledge Base:
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